1. Field of the Invention
This invention is concerned with structures of novel human leukocyte activating proteins and DNA encoding the protein. The invention is also concerned with recombinant plasmids and the transformants.
2. Prior art
Neutrophils migrate in response to increasing concentrations of chemotactic factors released from inflammatory sites. Activated neutrophils are recruited from the blood through the vessel wall to the infected site, and phagocytize invading bacteria or viruses. The phagosomes fuse with lysosomes, and the lysosomal enzymes and active oxygen radicals kill the invaders. Thus, the chemotactic factors released from inflammatory sites play an important role in activating neutrophil functions. After reaction by neutrophils in acute inflammation, monocytes and lymphocytes are involved in the immune response. In addition to other immune cells including cytotoxic lymphocytes, NK cells and macrophages, neutrophils exhibit a cytotoxic activity against tumor cells in vitro. In their tumorcidal actions, immune cells also migrate to tumor-growing sites, suggesting that tumor cells also produce a chemotactic factor for the immune cells. In this regard, it has been demonstrated that neoplastic cells of mouse and human origin produce chemotactic factors which mediate macrophage infiltration into tumor tissues. We have also identified LUCT/IL-8, which has been constitutively secreted from the carcinoma cell line LU65C (K. Suzuki et al., J. Exp. Med., 169, 1895-1901, 1989). The cells were established from human lung carcinoma tissue infiltrated by many neutrophils. The myeloid leukemia cell line ML-1 and glioma cells also produce LUCT/IL-8 constitutively (K. Suzuki et al., Immunol. Lett. 36, 71-82, 1993). The culture fluids of 97 human leukemia cell lines have been screened to search for a novel chemotactic protein. As a result, this invention has been produced.
Neutrophils seem to damage cancer cells in addition to macrophages and lymphocytes. Moreover, some histological tissues of cancer tissues are infiltrated with neutrophils. These are believed to be neutrophils response to chemotactic factors secreted from cells in these tissues.
Secretion of interleukins and damage of tumor cells are induced by activation of neutrophils, macrophages and lymphocytes. Thus, both natural and acquired immunities are enhanced. When the leukocyte activating factors are purified with large scale and simple procedures, those are used for diagnosis, therapy and determination after treatment. Further, these are also useful for basic research in activating mechanisms of neutrophils, macrophages and lymphocytes. We have found a neutrophil chemotactic factor, interleukin 8 (LUCT/IL-8) from culture fluid of cells established from human giant carcinoma cells. Then, we purified the factor (protein) and cloned the gene. IL-8 is about 8-kDa plain protein with pI 10.3. Two kinds of protein, 77-amino acid protein and 72-amino acid-protein are classified in IL-8, and possess the chemotactic activities with the same specific activity. Furthermore, IL-8 is a cytokine of inflammation and is detected in the serum of patients with chronic inflammation.
However, it has been thought that neutrophil chemotactic factor different from IL-8 is related with interaction between neutrophils and cancer cells.